Can an '88 Fiero be competitive in SSM?

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Series8217
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Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

After how well my car performed at Evo School over the weekend with my current setup, I'm looking more into SCCA's Super Street Modified (SSM) class. My car wouldn't be competitive with it's heavy, relatively underpowered LQ1, but with an appropriate drivetrain (Ecotec Turbo?) the Fiero can meet the minimum weight for its class. It can also fit some pretty big tires with minor modifications (coilovers). All of my handling modifications are permitted in SSM.... except in the rear. The '88 rear suspension geometry is pretty bad without relocating the lateral links to raise the roll center and improve the camber curve.

SSM allows any modifications from Stock, Street Touring and Street Prepared. Picking and choosing between the allowances is permitted. There are also additional modifications permitted such as engine swaps (same manufacturer as engine block) and suspension components are unrestricted (as long as they use original attachment points).

The only major reason I can't run my car in SSM is because of the fieroguru lateral link relocation brackets I'm using to correct the rear camber curve and raise the roll center on the '88 rear suspension.

In SSM, moving the factory pivot points is explicitly not allowed. The subframe also cannot be relocated.

This leaves a few obvious options:
* Find a way to run an absurd amount of static negative camber, sacrificing straight-line acceleration
* Move the strut top inward as far as possible
* Limit roll with springs and swaybars

From Street Touring (14.8.C)
The following allowances apply to strut-type suspensions. Adjustable
camber plates may be installed at the top of the strut and the original
upper mounting holes may be slotted.
The drilling of holes in order to
perform the installation is permitted. The center clearance hole may
not be modified. Any type of bearing or bushing may be used in the
adjustable camber plate attachment to the strut. The installation may
incorporate an alternate upper spring perch/seat and/or mounting
block (bearing mount).
Any ride height change resulting from installation
of camber plates is allowed. Caster changes resulting from the
use of camber plates are permitted.
It would take ~3" of lateral movement at the strut top to achieve the same camber curve improvement as the 1.5" lateral link drop brackets. Even with a carefully designed camber plate, it wouldn't be possible to achieve that much movement while still complying with "The center clearance hole may not be modified".

(14.8.I) of Street Touring also provides a relevant allowance:
On strut-equipped cars, the strut’s lower integral mounting bracket,
for attachment to the upright or spindle, is unrestricted provided it attaches
to the standard location. Any resulting change to the position
of the strut centerline is allowed.
Such brackets shall serve no other
purpose. This does not allow for changes to the integral steering arm
on cars that have the steering arm integrated with the strut body.
However, I don't see how the strut angle could be increased by redesigning the strut mount bracket on an '88 Fiero.
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Re: Can an '88 Fiero be competitive in SSM?

Post by fieroguru »

I have the tops of the struts pulled in on my 88 by 1". When I get to an actual computer I can send you pics.
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Re: Can an '88 Fiero be competitive in SSM?

Post by The Dark Side of Will »

Are lowering knuckles/spindles permitted?

You could make the argument that FieroGuru's brackets amount to lowering knuckles which you are running at higher than stock ride height.

Also, are knuckle-end pivot changes expressly forbidden, or only chassis-end pivot changes?
Seems like *if* you're allowed to run aftermarket knuckles, you have to be allowed to move the knuckle end pivots, as there's not a good way to scrutineer a small change to the pivot location if all the components are aftermarket.
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Re: Can an '88 Fiero be competitive in SSM?

Post by fieroguru »

Here are some pics of the strut top relocation:
Image
Image
Image
Image
Image

I am planning to run this strut top mod in addition to my lateral link relocation brackets with a small amount of lowering on my personal car.
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

That looks pretty nice Paul, but you can't run that in SSM. "The center clearance hole may not be modified." I don't see how cutting off the "ridge" would get past that rule.
The Dark Side of Will wrote:Are lowering knuckles/spindles permitted?

You could make the argument that FieroGuru's brackets amount to lowering knuckles which you are running at higher than stock ride height.

Also, are knuckle-end pivot changes expressly forbidden, or only chassis-end pivot changes?
Seems like *if* you're allowed to run aftermarket knuckles, you have to be allowed to move the knuckle end pivots, as there's not a good way to scrutineer a small change to the pivot location if all the components are aftermarket.
Above, I referenced the two strut-specific rules that are relevant.

Here's the other rule that matters:
Street Modified 16.1.E
Suspension components are unrestricted as long as they use the
original attachment points.
For the purposes of this rule, “suspen-
sion” is defined as any item that is designed to move when a wheel
is deflected vertically. This includes shocks/struts, control arms,
steering knuckles, uprights, etc., but not tie rods, steering racks, and
subframes. In addition, shock absorber/strut upper mounts are to be
considered suspension components.
I don't know if "original attachment points" means that the geometry of the knuckles/uprights needs to be the same as stock, but that is how I was interpreting it.

I'll do some research to see if the equivalent of a drop spindle is allowed.
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

I can't find an existing official statement, but there is discussion of drop spindles and just making sure the body points are the same:
http://www.nissanroadracing.com/showpos ... ostcount=5
http://www.miataturbo.net/race-prep-75/ ... post970594

If "attachment points" means the points on the body side only.... ohhh that would be so nice.

I think the only way to drop 200 lbs of weight off my car (to get to the minimum weight for the class) would be to swap in an Ecotec Turbo though.
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

Minimum weight:
MiNiMuM weightCAlCulAtioNS(without dRiveR):
FWD: 1350 lbs + 125 lbs per liter
RWD: 1600 lbs + 200 lbs per liter
AWD: 1600 lbs + 300 lbs per liter
Supercharged or Turbocharged SSM engines: Add 1.4L to the actual
displacement.
Rear wheel weight greater than 51%: +25 lbs per liter
Tire width 275mm or less (all): -200 lbs
Regardless of the weight formulas above, no car will be required to
weigh more than 2900 lbs.
So with a 3.4L DOHC V6 and 215/275 tires (my current setup), minimum weight is 2165. Same with the Ecotec (2.0L + 1.4L for the turbo). With wider tires it bumps up to 2365. If I turbo the DOHC, minimum weight goes up to 2480. If I add massive tires (255/335) as well, minimum weight is 2680. That's plausible. I think it's better to aim for the lighter build, since the cost and complexity of the build balloons... bigger more expensive brakes, bigger more expensive transmission, bigger more expensive tires... and so on.

My previous car with the 3.4 DOHC was mostly stripped out, with stock brakes, wheels, tires and seats weighed 2720 without a driver.

Assuming the turbo ecotec takes 200 lbs off the car.... the minimum weight is still probably out of reach without a carbon fiber shell, seats, race battery, and some other trickery, but that might not be the end of the world.

The cars that dominate SSM are FD RX7s and Miatas. Corvettes and 2nd-gen MR2s run in the class as well. The RX7s get down to 2500 lbs or so. I think that's doable with an Ecotec and a careful car diet, as well as careful selection of components for fabricating swap parts such as the exhaust.
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Re: Can an '88 Fiero be competitive in SSM?

Post by The Dark Side of Will »

Based on the rules you cited, you could certainly make an argument that you are running the suspension at higher than stock ride height... that's what the pivots are doing.

You haven't changed the upper pivot of the strut, or the attachment of the struct to the knuckle. The arrangement of the original pivots remains constant... it's just that the ride height is different.

Now if they include the relationship of the pivots to the wheel axis with the geometry that cant' be changed, then it wouldn't fly. That's why I was asking about lowering spindles... if those are allowed for non-strut applications, then I think your setup should be legal.
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Re: Can an '88 Fiero be competitive in SSM?

Post by The Dark Side of Will »

Series8217 wrote:My previous car with the 3.4 DOHC was mostly stripped out, with stock brakes, wheels, tires and seats weighed 2720 without a driver.
Interesting that a DOHC car ends up that light. My Northstar car was 2895, but that's full weight with the spare and jumper cables still in the front compartment.

A 3.6 instead of the 3.4 would probably shed 100# right off the bat.

FD's and Mjatas are tough cars to beat in an autoX environment.
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

The Dark Side of Will wrote:Based on the rules you cited, you could certainly make an argument that you are running the suspension at higher than stock ride height... that's what the pivots are doing.

You haven't changed the upper pivot of the strut, or the attachment of the struct to the knuckle. The arrangement of the original pivots remains constant... it's just that the ride height is different.

Now if they include the relationship of the pivots to the wheel axis with the geometry that cant' be changed, then it wouldn't fly. That's why I was asking about lowering spindles... if those are allowed for non-strut applications, then I think your setup should be legal.
Based on the interpretations I cited, "attachment points" refers only to those on the body/frame, thus permitting drop spindles and outer link pivot relocation.

More: http://www.sccaforums.com/forums/aft/32199#278035
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

Weighed my 3.4 DOHC Fiero today at Lang Racing Development (http://www.langracing.com). It's 2780 lbs with no driver and 1/2 tank of gas. Lighter than I expected! Full details here.
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Re: Can an '88 Fiero be competitive in SSM?

Post by Series8217 »

I won't be updating this thread anymore, mainly because I'm aiming for Time Trials now. The local autocross scene is getting a bit annoying because it's highly overcrowded. I've been doing a lot of track days lately and I prefer the 80+ minutes per day of track time running HPDE with NASA, vs 4 minutes on course at a typical SCCA Autocross Championship. The practices are only slightly more tolerable, with ~12 minutes worth of runs, but an hour or two chasing cones as a work assignment.
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